KR0185668B1 - Copolymer latex from esters of(meth)acrylic acid and vinyl esters of branched chain carboxylic acids and preparation thereof - Google Patents

Abstract

Copolymers of esters of (meth) acrylic acid and vinyl esters of branched carboxylic acids, latexes containing such copolymers, their preparation, coating compositions composed of the latexes, and redispersibility formed by physical drying of the latexes Solid polymer products such as latex powders.

The copolymer provides an attractive combination of latex and coating properties.

Description

Copolymer latex prepared from esters of (mat) acrylic acid and vinyl esters of branched carboxylic acids and a method for producing the same

1 is a triangular diagram showing the starting comonomer composition in which the blackened area contains MMA-2-EHA-VEOVA9.

FIG. 2 is a triangular diagram showing the preferred starting comonomer composition in which the blackened area contains MMA-2-EHA-VEOVA9.

3 is a graph showing the relationship between applied force and elongation.

The present invention provides a copolymer of an ester of (mat) acrylic acid and a vinyl ester of a side chain carboxylic acid, an latex containing the copolymer, preparation of the copolymer, a coating composition composed of the latex, and the latex. It relates to a solid polymer composition formed by drying, such as a redispersible latex powder.

British Patent No. 967,479 discloses in a modified emulsion using a free radical initiator in the temperature range of 0 ° C-90 ° C.

(1) vinyl esters of saturated aliphatic mono carboxylic acids, with carboxyl groups bonded to tertiary and / or quaternary carbon atoms,

(2) alkyl esters of polymerizable α, β-ethylenically unsaturated carboxylic acids, and

(3) Practically describes a method for producing a stable latex, comprising copolymerizing a monomer mixture containing 0.5-5% by weight of α, β-ethylenically unsaturated carboxylic acid, based on the total monomer weight.

More specifically in Examples I-IX, a monomer premix composition is used as starting material, which is ethyl acrylate or propyl acrylate or methyl methacrylate as the only alkyl ester of the α, β-ethylenically unsaturated carboxylic acid component. On the other hand, as the vinyl ester of the saturated branched aliphatic monocarboxylic acid component, a mixture of various carboxylic acids is applied, in particular, containing 7-19 carbon atoms.

In addition, in the fourth and fourth claims of the present patent, methacrylic acid and vinyl pivalate in a ratio of 60-82 parts of ethyl acrylate, 17-39 parts of vinyl pivalate and 1-3 parts of methacrylic acid, and Combinations of ethyl acrylates have been mentioned as preferred combinations of starting monomers.

It has been found that the process only provides insufficient polymerization yield so that the latex obtained still contains a significant amount of residual monomer. The presence of free monomers in latex is considered disadvantageous. These glass monomers, which substantially contribute to the odour of latex and latex powders, have a detrimental effect on latex stability and, in connection with coating applications, also detrimental to the hardness, outdoor durability and blocking resistance of the film formed by drying the latex. Influence is shown.

In addition, in view of toxicity, it is preferable to reduce the free monomer.

For example, much effort has been made in the past to improve these polymerization yields, as well as the properties of the films finally formed after drying of the latex included in the coating composition.

U.S. Patent No. 4,397,984,

(a) 30-80% by weight of alkyl acrylate or a mixture of these compounds and di (alkyl) maleate, wherein the alkyl group is C _4-8 ;

(b) 8-30% by weight acrylic acid and / or methacrylic acid;

(c) 0-50% by weight of vinyl propionate vinyl acetate, methyl acrylate, ethyl acrylate and / or vinyl α-branched monocarboxylate containing 10 carbon atoms in the carboxylic acid residue;

(d) 0-5% by weight of acrylamide, methacrylamide, vinylsulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid and / or acrylonitrile; And

(e) Describes aqueous paper coating compositions, consisting essentially of an emulsion copolymer consisting of 0-3% by weight of crosslinking monomers in the form of an aqueous dispersion and a finely ground pigment, as the sole binder or midpoint agent. .

No further acceptable conversion near the theoretical expected yield of polymerization could be obtained; This results in the above mentioned unattractive coating film properties and toxicity.

However, due to the large differences in the reactivity of the individual monomers, it is well known to those skilled in the art that alkyl methacrylates and / or alkyl acrylates and vinyl esters with large branched carbon chains are quite difficult to copolymerize into substantially random copolymers. It's a concept that still exists. Therefore, copolymerization of monomer pairs into polymer dispersions at low temperatures, which exhibit the attractive properties of coating films, can be inferred from VeoVa Technical Manual VM 2.1, page 7 and 8, Technical Bulletin, June 1988 (VeoVa Registered trademark), which has been considered to be a bit difficult or even impossible.

The concept can be derived from the speech held during the ATIPIC Meeting Louvain-la-Neuve in Belgium on September 11, 1989, and during the NVVT Meeting in Rotterdam, Netherlands, on May 23, 1989.

In addition, theoretical expected yields cannot be reached because some of the monomers do not polymerize and cause unattractive properties as mentioned above.

Containing copolymers of vinyl acetate and vinyl esters of one or more tertiary carboxylic acids, because of the growing need for environmentally friendly aqueous coatings, which have more attractive properties and / or are obtained by more reliable and efficient copolymerization. There is another strong research effort towards the development of latex. Copolymers containing latex are known to exhibit suitable properties for use in coating applications. Known embodiments of such copolymer compositions are, for example, known from European Patent Application No. 315278 and Non-US Patent No. 3,654,209 when dried in the mortar mixture, as such, or to form a latex powder. It is used as a base material for paint, matte and silk finish emulsion paint.

Due to the demands of the modern coating industry, such copolymer compositions are expected to further improve the mechanical properties, chemical resistance and water resistance of the finally obtained coating films containing these copolymers after the coating composition has dried. .

More specifically, it will be appreciated that there is a strong need to improve the properties of latex in order to meet the needs of glossy emulsion paints and antiseptic paints. In addition, to be manufactured in an economically attractive way. There is a need for an efficient and reliable method for producing the latex.

As a result of extensive research and experiments, such copolymers are surprisingly aimed at showing a combination of the latex stability and the chemical stability, alkali resistance and light resistance of the latex film, as well as very attractive properties such as high monomer conversion and freezing. The composition was spread out.

Thus, the group of copolymers provided is

(a) methyl methacrylate;

(b) 2-ethylhexyl acrylate;

(c) Vesatic 9, which represents a tertiary aliphatic carboxylic acid containing nine carbons, with the acid portion optionally mixed with a vinyl ester trace of Versatic-10 acid, representing a tertiary aliphatic carboxylic acid containing ten carbons. Vinyl esters of acids (registered trademark); And

(d) acrylic acid, methacrylic acid, acrylamide, methacrylamide, diacetone acrylamide and sodium vinyl sulfonate and mixtures thereof, in amounts of 0.5-5% by weight relative to the total weight of monomers Is most preferred), comprising stabilizing monomers selected from the group consisting of: wherein the weight percent of each of components (a), (b) and (c) is the same in triangular relative to the total weight of these components The following equations each describing a composition having a performance contour:

Equation 1

(In Equation 1 above, Tg represents a glass transition temperature of a value in the range of -10 ° C to 50 ° C, WA represents a water absorption of 30% m / m or less, measured as described later, and WS is subsequently As noted, water spot value is at least 7 after 24 hours, X ₁ represents the weight percent of component (a), X ₂ represents the weight percent of component (b), and X ₃ represents the component ( the values of X ₁ , X ₂ and X ₃ , expressed in weight percent of c) and calculated based on the weight of components (a), (b) and (c), are in the range of 5-95 and the coefficients a ₁ -a The exact values of ₇ and b ₁ -b ₂ can be derived by using such comonomers as starting materials, which are calculated to simultaneously satisfy the specific form of the stabilizing monomer and surfactant applied and its concentration). It is done.

According to a preferred embodiment of the invention, there is provided a copolymer which can be derived from components (a)-(d), wherein component (d) is in an amount of 0.5-2% by weight, preferably about 1% by weight The following equations each describe a composition consisting of acrylic acid and each weight percent of components (a), (b) and (c) to be calculated for the total weight of the total amount of the components :

[Equation 2]

Are simultaneously satisfied, and in Equation 2, Tg, WA, and WS have the same value as previously defined, and X ₁ , X _2, and X ₃ have the same meaning and value as mentioned above.

Those skilled in the art will appreciate that the starting comonomer composition containing monomers (a), (b) and (c) in the proportions satisfying the above-mentioned equations IV-VI are shown as areas blacked in FIG. will be.

The term vinyl ester trace amounts of Versatic-10 acid as used throughout this specification is any mixture of Versatic acid vinyl esters, ie at most 30% by weight (calculated based on the total weight of the vinyl ester mixture), preferably 10 It means that up to weight percent, more preferably up to 5 weight percent will be constituted by Versatic 10 acid vinyl ester.

Since the vinyl ester of Versatic-9 acid is optionally mixed with the vinyl ester of Versatic-10 acid, VeoVa 9® optionally mixed with VeoVa 10® is preferably used.

A more preferred group of copolymers may be derived from comonomer mixtures, wherein the weight fractions of components (a), (b) and (c) simultaneously satisfy the following equation VII-IX:

[Equation 3]

In Equation 3, Tg 'has a value in the range of 0-50 ° C., WA' has a value of 25% or less, and WS 'is applied to the coating film at least after 24 hours as defined thereafter. It has a value of 8 and component (d) is 1 weight% of acrylic acid.

It will be appreciated that these preferred starting comonomer compositions, containing monomers (a), (b) and (c) in suitable proportions satisfying the above-mentioned equations VII-IX, are shown in blackened areas in FIG. will be.

One of the most preferred embodiments of the inventive copolymers is

(a) 15-32% by weight methyl methacrylate;

(b) 10-25% by weight ethyl hexylacrylate;

(c) 50-65% by weight VeoVa9;

(d) formed by those characterized in that they can be derived from a starting comonomer mixture comprising 0.5-2% by weight acrylic acid or acrylamide.

It has also been found that by using only one copolymerizable stabilizing component (d) it is possible to obtain latexes having an acceptable low free monomer content, ie up to 2% by weight, based on solids content, and with good stability.

The present invention also relates to latex, latex and preferably polymer components containing 30-60% by weight of copolymers as described above, more preferably 40-50% by weight of polymer components. A coating composition composed of a pigment, a solid copolymer product formed by physical drying of the latex or coating, and a redispersible latex powder formed by physical drying of the latex, and a coating composition derived from the powder Will be understood.

Another aspect of the invention relates to a process for the preparation of latexes containing copolymers as described above.

In addition, these attractive results can be achieved not only by carrying out the thermal initiation but also the redox initiation of the starting reaction mixture, which is also rather independent of the actual relative proportions of the components (a)-(d) in the indicated ranges. I found that. More preferably, thermal initiation of the reaction mixture is applied.

Copolymers containing latex according to the invention are known in the art and can be prepared under conditions involving temperatures of usually 20-100 ° C. More particularly, the manufacturing process is carried out at a temperature of 60-100 ° C., preferably 75-85 ° C. when thermal initiation is applied.

In the reaction mixture, additional stabilizers to be copolymerized optionally, one or more polymerization initiators and optionally buffers are included, but more preferably no buffer is used.

The stabilizer suitably comprises about 1-4% by weight of the total amount of latex. Stabilizers used in latex are believed to have a favorable effect on the stability of the latex during the polymerization process and in particular on the reaction mixture, which facilitates the formation of micelles and optionally nonionic surfactants from which copolymers are formed, At least one anionic surfactant believed to contribute to stability; Or at least one mixed anionic / nonionic type of surfactant.

Suitable anionic surfactants include alkylaryl sulfonates such as alkylbenzene sulfonates; Sulfosuccinic acid ester salts; Of alkyl sulfates, alkyl sulfonates, alkyl aryl phosphate sulfates of hydroxyethyl esters of monocarboxylic acids, sulfates of alkylphenoxypolyethoxyethanols, sulfonates of hydroxypropyl esters of monocarboxylic acids and monocarboxylic acids Sulfate of monoglycerides, wherein the compounds are C ₁₂ -C ₂₄ ; Salts of C _9-19 monocarboxylic acids. Suitably latex 0.05-1% by weight will comprise anionic surfactants, preferably 0.1-0.5%.

Suitable nonionic surfactants are ethylene oxide or propylene oxide, such as the general formula RC ₆ H ₄ -O- (CH ₂ -CH ₂ -O) _n -H, where R is a C _6-16 , in particular a C _8-9 alkyl group A reaction product of an alkylene oxide and hydroxy compounds, such as a compound of (n). Suitably C _6-20 alcohols such as octyl, lauryl or cetyl alcohol and or propylene glycol ethers with ethylene oxide. Suitably, 0.5-2% by weight of the latex may comprise a nonionic surfactant.

Suitable surfactants of the mixed anionic / nonionic type include sulfonates based on alkyl aryl polyglycol ethers.

Preferably, both anionic and nonionic surfactants are used. Especially preferred is the use of alkyl aryl sulfonates with RC ₆ H ₄ -O- (CH ₂ -CH ₂ -O) _n -H compounds, such as for example nonyl phenol ethoxyl.

Suitable initiators are mixtures which form free radicals under reaction conditions for aqueous emulsion polymerization by thermal decomposition, redox reactions or photoinitiation. Initiators include organic water soluble peroxides, hydroperoxides and persulfates. Examples are hydrogen peroxide and sodium, ammonium, or, in particular, potassium persulfate. By weight of the reaction mixture, 0.1-1%, preferably 0.4-0.7%, of initiator is suitably used.

If necessary, suitable buffers for use in the polymerization process are water soluble compounds that can prevent the pH of the mixture from dropping below about 4. Preferred buffers include serving and organic acids, suitable acetic acid, or alkali metal carbonates or bicarbonates or acetates.

According to a preferred embodiment of the process of the invention, thermal initiation is applied and the reaction is carried out in an inert atmosphere and nitrogen is suitably used to flush the reactor before the start of the reaction.

According to another preferred embodiment of the process of the invention, the emulsion premix is a part of one or more surfactants and part of one or more redox initiators and demineralized water from comonomers (a), (b), (c) and (d) Is manufactured in. The reactor is flushed with nitrogen and filled with approximately the same amount of demineralized water and the remaining amount of surfactant (s) and initiator.

The reactor is heated to a certain range, such as 80 ° C., the nitrogen stream is stopped and the emulsion premix addition is started. The addition usually continues over a period of 2-5 hours while the first adjusted temperature is maintained. After the end of the addition of 1-3 hours of the premix, the subsequent polymerization period is usually used, for example at a temperature of 80 ° C.

After the subsequent polymerization, the latex obtained is cooled and filtered if necessary.

Generally, the latex obtained has a weight average particle size of 90-170 mm, depending on the total solids content of 30-60% by weight of the latex, preferably 40-50% by weight, and the surfactant ash between the emulsion premix and the initial reactor charge. Have a diameter.

Another aspect of the present invention relates to a latex produced by the method, and a copolymer formed upon physical drying of, for example, a latex forming a coating on a support, or a powder or concrete or other latex based final product to be reconstituted as a latex. It is about use of furnace.

Latex according to the present invention may find use in concrete, lacquers, paints, wood coatings, antiseptic paints, and woven coatings. They are particularly interesting for compounding lacquers and paints, due to their good film forming properties, water resistance, high pigment binding powder, flexibility, lack of film thickness, their alkali resistance and resistance to ultraviolet light. Paints containing latex of the present invention contain pigments and will usually contain other ingredients such as fillers, cosolvents, thickeners, dispersants, preservatives, corrosion inhibitors and defoamers.

It will therefore be appreciated that the coating compositions composed of the latex according to the invention and their formed solid copolymer products also form an aspect of the invention.

The invention will now be further described with reference to the following examples, although the scope is not limited to these specific embodiments.

Example 1

In a 3 liter reaction flask, one central and four peripheral glass openings were formed to fit a reflux condenser, stirrer, thermometer, nitrogen inlet tube, and emulsion premix inlet tube.

An emulsion premix was prepared by mixing the following ingredients in a given amount.

The reaction flask was washed with nitrogen and the following components were added:

+ Humifen SF90 is a registered trademark of the alkali sulfonate anionic surfactant.

++ Arcopal N230 is a registered trademark of the nonionic surfactant.

+++ VeoVa 9 is a registered trademark for vinyl esters of tertiary carboxylic acids containing 9 carbon atoms.

The components in the reaction flask are heated to 80 ° C. When the temperature reaches 80 ° C. the nitrogen stream is stopped and the addition of the emulsion premix is started. Monomer pre-emulsion was added regularly over 3 hours and the temperature of 80 degreeC was maintained. A maturation period of 2 hours (at the same temperature) was given. After heating, the latex was cooled and filtered if necessary. Typically these latexes have a total solids content of 45% and a weight average particle diameter of about 150 nm.

The latex obtained was tested for water absorption and material station resistance of the latex polymer film, while measured by monomer conversion, particle size, viscosity, minimum film formation temperature, glass transition temperature, tensile strength and yield value, surface hardness.

Example II-VI

Copolymer latexes were prepared from different sets of comonomers in the manner as described in Example I.

Each amount of constituent monomer applied in weight percent relative to the total starting composition and the relevant properties of the latex obtained are listed in Table 1 below.

Comparative Test Sample A was taken from a composition prepared according to British Patent No. 967,479.

** Comparative Test Sample B is generally used as a coating composition and is a commercially available Acronal 29D ™.

The water absorbency (thick film test method) of the latex polymer film and emulsion paint film was measured as described below.

A 2 mm thick wet film was applied to the polyethylene foil (latex was held on the foil by applying an automatic sealer on the foil edges). In order to avoid too fast evaporation of water and thus severe dry heat, the panels were covered with some water vapor permeable material and then stored at 20 ° C. above Tg for one week. The cover was removed after the transparent film was formed. After removing the glass panel, three pieces of 2 × 2 cm were cut from the film and weighed at almost 0.1 mg. They are stored in demineralized water at 23 ° C. and reweighed after 1,2,4,7 and finally 14 days (after removing excess water with a filter paper). The water absorbency is calculated from the observed weight gain. The average of three replicate measurements is averaged and the plot is usually plotted between the soak time and water absorption.

The water mark resistance of the latex polymer film as described below was measured.

A 200 micron wet latex film was applied onto the glass panel and dried for one week at 20 ° C. above Tg. If water droplets form on the film when cooled to 23 ° C, the panel is placed in a dark basement. Visualize the whitening effect visually after 5, 10, 15 and 60 minutes and 24 hours. A rating between 10 (if the film is not affected) and 0 (if the film is completely white) is measured every hour. After 1 hour, 4 points are added and divided by 4 (maximum score 40). If the film score is very high, it is worthwhile to continue the test for 23 hours and to grade the 24 hours from 0 to 10. The watch plate can be covered overnight to prevent evaporation of water droplets.

[Tensile strength measurement]

A 2 mm thick wet film was applied onto the polyethylene foil. The film is covered with some water vapor permeable material to prevent too fast evaporation of water and then stored at 40 ° C. for one week to dry. After the transparent film was formed, a test sample was prepared for molding purpose. The test sample has a length of 25.0 mm and a thickness of ± 1 mm.

The sample is then pulled to break in a tensile strength tester with a preliminary force of 0.5 N and a pulling speed of 500 mm / μm. The relationship between the applied force and the calculation is plotted in FIG.

Points to be considered are yield values and their corresponding elongations and failures at break and corresponding stretches. The first point refers to flexibility and the second point refers to the strength of the film.

[Stress-Strain]

Comparative Test Sample C ₁ is a composition made from vinyl acetate (49%), Veova 10 (trademark)) (32.5%), VeoVa 9 (trademark) (17.5%) and acrylic acid (1%).

** Comparative Test Sample C ₂ Acronal 290D ™, which is a commercially available coating composition derived from styrene and acrylate.

*** Comparative Test Sample C ₃ is Primal 388 ™ and is a commercially available coating composition derived only from acrylates.

**** Comparative Test Sample C ₄ is a composition made from methyl methacrylate (49.5%), butyl acrylate (49.5%) and acrylic acid (1%).

[Freezing Fusion Stability Test]

Latex is introduced into a 100 ml polyethylene bottle. After the pH was set to 8, the bottles were stored at −18 ° C. for 24 hours and then screened for stability failures.

The above was repeated five times except for the initial failure.

Claims (19)

(a) methyl methacrylate; (b) 2-ethyl hexyl acrylate; (c) The acid moiety contains 9 carbon atoms, with or without mixing, with or without 30% by weight of any mixture of Versatic-10 acid vielesters, wherein the acid moiety represents a tertiary aliphatic carboxylic acid containing 10 carbon atoms. Vinyl esters of Versatic-9 acid (registered trademark) representing tertiary aliphatic carboxylic acid, and (d) selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, methacrylamide, diacetone acrylamide and sodium vinyl sulfonate and mixtures thereof in an amount of 0.5-5% by weight relative to the total weight of the monomers Copolymers obtainable by polymerization of comonomer mixtures comprising stabilizing monomers, wherein the weight percentages of each of components (a), (b) and (c) are calculated relative to the total weight of these components And simultaneously satisfying Equations 1 below, each describing a composition having the same performance contour in a triangle. Equation 1 (In the above equation, Tg represents a glass transition temperature having a value in the range of -10 ° C to 50 ° C, WA represents a water absorption value of 30% m / m or less, and WS represents a water station value of 7 or more after 24 hours. spot value), X ₁ represents the weight percent of component (a), X ₂ represents the weight percent of component (b), X ₃ represents the weight percent of component (c), and each X ₁ , X Values of ₂ and X ₃ are in the range of 5 to 90 calculated on the basis of the total weight of components (a), (b) and (c)). The copolymer according to claim 1, wherein acrylic acid or acrylamide is used as the stabilizing monomer (d). 3. The vinyl ester of Versatic 9 acid according to claim 1 or 2, as component (c), mixed or not mixed with less than 5% by weight of the vinyl ester of Versatic 10 acid, calculated on the basis of the total weight of the vinyl ester mixture. Copolymer, characterized in that to use. The copolymer according to claim 1 or 2, wherein component (d) consists of 0.5-2% by weight of acrylic acid. The method according to claim 1, wherein the weight fractions of components (a), (b) and (c) respectively describe compositions having the same performance contours in triangular diagrams. [Equation 2] (In the above equation, Tg 'has a value in the range of 0-50 ° C., WA' has a value of 25% or less, and WS 'has a value of 8 or more after 24 hours when applied to a coating film) And component (d) is 1% by weight acrylic acid. The method of claim 1 or 2, comprising: (a) 15-32% by weight of methacrylate; (b) 10-25% ethylhexyl acrylate; (c) 50-65 weight percent VeoVa 9; And (d) copolymers, characterized in that they can be derived from a starting mixture comprising 0.5-2% by weight of acrylic acid or acrylamide. A latex containing 30-60% by weight of the copolymer of claim 1 as a polymer component. 8. The latex according to claim 7, wherein the polymer component is in an amount of 40-50% by weight. A coating composition comprising the latex of claim 7 and one or more pigments. A solid copolymer product formed by physical drying of the latex of claim 7. Solid copolymer product formed by physical drying of a coating according to claim 9. Redispersible latex powder formed by physical drying of the latexes according to claim 7. A coating composition based on the powder of claim 12. Process for preparing the latex containing the copolymer of claim 1 by polymerization of a comonomer mixture at a temperature in the range of 20 to 100 ° C., with or without a buffer, in the presence of an additional stabilizer and at least one polymerization initiator. . 15. The process according to claim 14, wherein 1 to 4% by weight of anionic surfactant and at least one nonionic surfactant is used as stabilizer. The alkylaryl sulfonate of claim 14 or 15, wherein the alkylaryl sulfonate is a compound RC ₆ H ₄ -O- (CH ₂ -CH ₂ -O) _n -H, wherein R represents a C _6-16 alkyl group, and n is 3 to 40 represent a number). 16. The method of claim 14 or 15, wherein peroxide, hydroperoxide or persulfate is used as initiator. 18. The process according to claim 17, wherein hydrogen peroxide and sodium, ammonium or potassium persulfate are used in an amount of 0.4 to 0.7% by weight based on the weight of the reaction mixture. 15. The method of claim 14, wherein borax and organic acids, or alkali metal carbonates or bicarbonates are used as buffers.